Cost-effective approaches in fabricating high-density 316L stainless steel via indirect SLS: using a novel coating process and water-atomized powder

Indirect selective laser sintering (indirect SLS), a metal additive manufacturing technology based on the forming-debinding-sintering process, can be used to fabricate high-density metal components. This study aimed to reduce its preparation cost, and was predominantly conducted from two aspects: developing a novel coating process and using low-cost water-atomized powder as raw materials. Firstly, compared with the stirring evaporation method, the filtration-drying method simplified the preparation process of coating powder, reduced the cost, and improved the uniformity of the resin coating. The gas-atomized 316L sintered parts prepared by this method exhibited excellent properties, with a relative density of 99.1%, a yield strength of 261.4 MPa, an ultimate tensile strength of 572.4 MPa, and a Vickers hardness of 140.9 HV 1 , all of which were superior to those of the stirring evaporation method. Secondly, the relative density of the green parts was crucial for sintering. The green parts prepared from water-atomized powder had a low relative density of merely 28.9%, resulting in the highest relative density of the sintered parts being only 93.9% and the sample losing its designed shape. Thirdly, by using a mixture of 50 wt.% water-atomized powders and 50 wt.% gas-atomized powders as raw materials, a 316L sintered sample with a relative density of 99.0% and maintaining its designed shape could be obtained. This mixture not only substantially decreased the raw material cost, but also enabled the mechanical properties of the samples to be comparable to those of the samples prepared solely with the pure gas-atomized powders.